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Module

Avoid using Eval extensively​

void Start() {
    Puerts.JsEnv env = new Puerts.JsEnv();
    env.Eval("const a = 3");

    ////// much later
    env.Eval("const a = function () {}");
}
void Start() {
    Puerts.JsEnv env = new Puerts.JsEnv();
    int a = env.Eval<int>(@"
        (function() {
            const a = 3
            return a;
        })()
    ");

    // a == 3
}

In fact, the Immediately Invoked Function Expression is a concept in JavaScript that is very similar to modules. It has an independent scope and can define its own output items, making it very convenient for encapsulating functionality.

ESM modules​

Starting with the Immediately Invoked Function Expression, the JavaScript ecosystem has developed many module specifications, with the most popular being the official JS standard: ESM.

PuerTS supports executing modules that follow the ESM specification.

You can add a helloworld.mjs file to any Resources directory:

import { world } from 'lib.mjs'
console.log('hello ' + world);

Add a lib.mjs file to any Resources directory:

const world = 'puerts'
export { world }

Then import it using JsEnv.ExecuteModule.

void Start() {
    Puerts.JsEnv env = new Puerts.JsEnv();
    env.ExecuteModule("helloworld.mjs")
}

It will output hello puertsin the console​

With the above approach, you can use Puerts to load and execute JS files without using Eval (and we do not recommend using it in your actual development).​

After writing JS in a separate file, the next step is to return to one of Puerts' focus areas: TypeScript (TS).